class Student(object):
    def __init__(self, name, score):
        self.__name = name
        self.__score = score

    def set_name(self, name):
        self.__name = name

    def set_score(self, score):
        if 0 <= score <= 100:
            self.__score = score
        else:
            raise ValueError('bad score')

    def get_name(self):
        return self.__name

    def get_score(self):
        return self.__score

    def print_score(std):
        print(f"{std.__name}:{std.__score}")

bart = Student('Bart', 100)
bart.set_score(50)
print(bart.get_name(), bart.get_score())
bart.print_score()